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Influence of transition metal additives and temperature on the rate of organohalide reduction by granular iron: Implications for reaction mechanisms

Paper ID Volume ID Publish Year Pages File Format Full-Text
48445 46507 2007 9 PDF Available
Title
Influence of transition metal additives and temperature on the rate of organohalide reduction by granular iron: Implications for reaction mechanisms
Abstract

This study provides mechanistic insights into the reduction of organohalides by granular iron as well as the origin of the rate enhancements typically observed when transition metals are added to the surface of granular iron. Using step-wise displacement plating of CuCl2, K2PdCl4 and K2PtCl4, different bimetallic and trimetallic reductants were prepared and characterized using a suite of analytical techniques that included energy filtered transmission electron microscopy (EFTEM). Results obtained from batch studies with the trimetals indicate that reactivity enhancements of 1,1,1-trichloroethane (1,1,1-TCA) reduction are controlled by the chemical identity of the transition metal additive at the liquid/solid interface. Temperature-dependent studies involving iron and bimetals revealed that rates of 1,1,1-TCA reduction increased exponentially with increasing temperature. A systematic shift in product distribution towards more fully hydrogenated products was also observed as the overall rate of 1,1,1-TCA reduction increased. Collectively, these results support recent studies, which suggest that atomic hydrogen is involved in the reduction of alkyl polyhalides by granular iron and bimetallic reductants.

Keywords
Bimetallic reductants; Organohalide; 1,1,1-Trichloroethane; Zero-valent iron
First Page Preview
Influence of transition metal additives and temperature on the rate of organohalide reduction by granular iron: Implications for reaction mechanisms
Publisher
Database: Elsevier - ScienceDirect
Journal: Applied Catalysis B: Environmental - Volume 76, Issues 3–4, 15 November 2007, Pages 348–356
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Catalysis